OBJECTIVE: Our purpose was to investigate Bcl-2 and Fas expression in human eutopic and ectopic endometrium during the menstrual cycle in relation to endometrial cell apoptosis.

STUDY DESIGN: Eutopic and ectopic endometrial samples were obtained from 29 patients with endometriosis, and eutopic endometrial tissue samples were obtained from 9 patients with uterine myoma. Bcl-2 and Fas expression were examined by immunohistochemical staining with specific monoclonal antibodies; Bcl-2 expression in eutopic endometrium was also examined by Western blotting and apoptotic cells were detected by the labeling of deoxyribonucleic acid fragments.

RESULTS: In eutopic endometrium Bcl-2 was strongly expressed during the proliferative phase. Endometrial glandular cells showed evidence of cyclic changes in Bcl-2 expression, but cyclic changes were not apparent in peritoneal and ovarian endometriotic tissue. Fas expression was observed on glandular cells but not on stromal cells, and no cyclic changes in expression occurred in either ectopic or eutopic endometrium. Apoptotic cells were observed primarily in the glandular cells of the basal layer in eutopic endometrium during the late secretory and menstrual phases.

CONCLUSION: The current study indicated that there was no apparent correlation between Bcl-2 or Fas expression with endometrial cell apoptosis. The absence of cyclic changes in Bcl-2 expression in ectopic endometrium implied a difference in the mechanisms of proliferation or differentiation between eutopic and ectopic endometrium.(Am J Obstet Gynecol 1997;176:360-8.)